Overheating/pinging protection, function - GF07.61-P-4027MIS

ENGINE 272.9 in MODEL 221.0 /1 as of model year 2009 / AEJ 08 

ENGINE 273.9 in MODEL 216.3, 221.0 /1 as of model year 2009 / AEJ 08 

Function requirements for overheating/knock protection, general points 

• Circuit 87M ON (engine control ON)
• Engine running

Overheating/knock protection, general points 

In case of thermal overload, the overheating/knock protection protects against engine damage and overheating damage to the firewall catalytic converter.

The ME-SFI [ME] control unit (N3/10) controls the overheating/ knock protection according to information from the following sensors:

• Hot film MAF sensor (B2/5), engine load
• Intake air temperature sensor (B2/5b1)
• Coolant temperature sensor (B11/4)
• Crankshaft Hall sensor (B70), engine speed

Overheating/knock protection function sequence 

If the coolant or intake air temperature is too high, the ME-SFI [ME] control unit no longer fully opens the throttle valve actuator (M16/6), depending on engine speed and load. The ME-SFI [ME] control unit shortens the injection time at the fuel injection valves (Y62) according to the lower air mass.

The ME-SFI [ME] control unit also actuates the heating element in the three-disk thermostat valve (Y110), so that the three-disk thermostat is fully open and all the coolant is cooled by the engine radiator.

	Electrical function schematic, overheating/ knock protection function ME	Model 216	PE07.61-P-2777-97CAB
		Model 221	PE07.61-P-2777-97SAB
	Component description for ME-SFI [ME] control unit	N3/10 Engine 272 except 272.974 (Hybrid)	GF07.61-P-6000MIS
		N3/10 Engine 272.974 (Hybrid)	GF07.61-P-6000MEH
		N3/10 Engine 273	GF07.61-P-6000MLS